Researchers at the University of Chicago Department of Medicine say they have found what may be a trigger for celiac disease, which is a genetic inability to digest the gluten found in certain grains.

A study published in the journal Nature found that two molecules appear to signal an inflammatory response in the body.

One is interleukin 15, a protein that activates immune cells called T lymphocytes. The other is retinoic acid, a molecule derived from vitamin A that helps human cells grow.

When exposed to these two compounds, the digestive tracts of people with celiac disease get inflamed, the team said.

Often people with the condition experience diarrhea, nausea, stomach cramps, weight loss, fatigue or anemia, according to the National Institutes of Health (NIH).

Grains that may cause this reaction include wheat, barley and rye.

Researchers noted that the results of their study indicate that vitamin A, which can be used to treat inflammation, may have more negative effects than benefits when given to people with celiac disease.

They suggested that further research be done into other food allergies, many of whose mechanisms are currently unknown.